The 305-metre Arecibo Telescope in Puerto
Rico showing the Gregorian secondary reflector which is moved
across the support structure to track the target star across
the sky. Photo: Tony A

The Pioneer 10 signal. To test that the complete receiving
system is operating as expected, each night a search is made
for the signal from the Pioneer 10 space probe. Launched in
1972, this is now 6.5 billion miles from Earth but is still
transmitting a signal of a few watts. The Pioneer 10 signal
would not be seen in a single scan, but shows up as a drifting
signal when many scans are plotted together as shown above.

The Lovell Telescope has joined with the 305-metre Arecibo Telescope
in Puerto Rico to take part in what is the most sensitive and
comprehensive search yet undertaken for possible radio signals
from extraterrestrial civilisations beyond our Solar System.
The 5 year research programme, project Phoenix, is led by the
privately-funded SETI Institute. The aim is to observe 1000
of the nearest Sun-like star systems. It is hoped that an advanced
civilisation might exist on a planet within one of these systems.
Observations are scheduled for 40 nights each year.

Arecibo

The Arecibo Telescope uses a 56-million channel receiver to
make initial signal detections. Information about those signals
which are not in the data bank of known terrestrial signals,
are passed on to two further sets of identical receivers at
Arecibo and Jodrell Bank. Due to the rotation of the Earth,
and the great distance separating Jodrell Bank and Arecibo,
a signal from outside the Solar System will have precisely calculable
differences when observed at the two observatories. This allows
an extraterrestrial signal, should one be found, to be distinguished
from those originating on, or near, the Earth.